Napoleon saw Berthier’s brief look of surprise. The order to shift the position of the Guard was a clear admission that the Emperor was anxious about the fate of Davout and his corps.

‘What if it is Archduke John?’ Berthier asked quietly.

‘It isn’t.’

Napoleon strode towards the white mare being held by one of his grooms. ‘Make a step!’

The groom obediently released the reins and cupped both hands as he bent down. Once Napoleon was hoisted into the saddle he took the reins and called out to Berthier.‘If anything happens, if the enemy make any further movements, send word to me at once!’

‘Yes, sire.’

Napoleon turned his horse away and spurred it into a gallop across the heart of the plain towards the Grand Army’s right flank. As he rode he was deep in thought and ignored the cheers of the men he passed by. Despite what he had said to Berthier, he feared that the attack on Davout might well herald the arrival of Archduke John. The right flank of the Grand Army would be vulnerable to the Austrian reinforcements.

Ahead of him clouds of gunpowder smoke billowed across the eastern horizon, blotting out the first rays of the sun. Napoleon raced to the corps headquarters on the edge of the village of Glinzendorf, where he found Marshal Davout’s staff hurriedly packing their document chests on to wagons. The crack of muskets and thud of guns came from less than half a mile to the east.

‘You!’ Napoleon pointed at the nearest staff officer. ‘Where is Davout?’

‘The marshal has gone to the flank, sire. Some of our units broke when the enemy attacked. Davout went to rally the men.’

Napoleon wheeled his horse round and rode on through the reserve formations of Davout’s corps until he passed over a small rise and saw the battle on the flank raging across the landscape before him. The edge of the sun had risen over the rim of the distant hills and by its light Napoleon could see the dark columns of the enemy tramping forward. They had crossed the Russbach and struck Davout’s men as the latter were forming up for their own attack. Tiny figures of fleeing soldiers were still spreading about across the plain as they ran from the enemy. The second French line had held firm and was now locked in an exchange of volleys with the Austrians. To the right of the line Napoleon could make out a group of officers, and he spurred his horse on.

As he rode up to Davout the marshal was busy issuing orders to his subordinates to steady their men and hold their ground. Some distance to the rear Napoleon saw the horse artillery and the cavalry he had sent to cover the army’s flank.

‘Sire.’ Davout greeted him with an anxious look. ‘I didn’t expect to see you here.’

‘No?’